A La / Nd / Ce / Ga / V / Sn / W doped Bi3TiNbO9 high-temperature piezoelectric ceramic material and its preparation method

Abstract

This invention discloses a La / Nd / Ce / Ga / V / Sn / W doped Bi3TiNbO9 high-temperature piezoelectric ceramic material and its preparation method, targeting the Bi at the A-site of the Bi3TiNbO9 ceramic material. 3+ Ions, using La 3+ 、Nd 3+ Ce 4+ The complex high-valence ion [La] 0.2 Nd 0.4 Ce 0.4 ] 3.4+ Doping substitution is performed on Ti at the B site. 4+ 、Nb 5+ Ions, using Ga 3+ V 5+ Sn 4+ W 6+ Composition of complex high-valence ions [Ga 0.3 V 0.7 ] 4.4+ 、[Sn 0.35 W 0.65 ] 5.3+ By employing doping substitution and the aforementioned composite doping modification, the piezoelectric properties and high-temperature resistivity are improved while maintaining a high Curie temperature. This results in a novel, environmentally friendly piezoelectric ceramic material with excellent overall electrical properties. This material exhibits good high-temperature stability and has broad application prospects in high-temperature fields. The preparation method of this invention utilizes advanced ceramic preparation technology, with low firing temperature, low preparation cost, simple and easy-to-operate process, and easily controllable influencing factors, making it suitable for mass industrial production and facilitating its promotion and application.

Description

Technical Field

[0001] This invention relates to the field of piezoelectric ceramic materials technology, and in particular to a doped bismuth layered bismuth niobate titanate high-temperature piezoelectric ceramic material and its preparation method. Background Technology

[0002] Currently, the most widely used piezoelectric ceramic material is lead zirconate titanate piezoelectric ceramic. However, because these ceramics contain lead, they pose a threat to the environment and human health during production, use, and disposal. Furthermore, the Curie temperature of these ceramics is generally below 400℃, and due to depolarization, they cannot function properly above this temperature. With the rapid development of aerospace, geological exploration, and other fields, and in line with the needs of sustainable development, it is necessary to seek an environmentally friendly piezoelectric material with a high Curie temperature and excellent piezoelectric properties.

[0003] Bismuth layered ceramics possess characteristics such as high Curie temperature, low dielectric loss, significant anisotropy of electromechanical coupling coefficient, high resistivity, no pollution, low leakage current, and excellent ferroelectric properties, making them promising candidate materials for high-temperature environments. Bismuth layered ceramic materials are composed of (Bi₂O₂). 2+ It is composed of alternating layers of perovskite-like lattice structure, and its general chemical formula is (Bi₂O₂). 2+ (A m-1 B m O 3m+1 ) 2- Bi3TiNbO9 (BTN) is a typical bismuth layered ferroelectric material, where A is a 12-coordinated Bi. 3+ B is a 6-coordinate Ti 4+ and Nb 5+ m = 2, composed of a fluorite-like structure (Bi₂O₂) 2+ Layered and perovskite-like structure (BiTiNbO7) 2- The material consists of layers and has a very high Curie temperature (T). C It has good thermal stability and fatigue resistance (≈914℃), but a very low piezoelectric constant (d). 33 (≈4pC / N). Therefore, how to improve piezoelectric activity while maintaining a high Curie temperature and obtain BTN piezoelectric ceramic materials with excellent comprehensive electrical properties has become an important research topic in the field of high-temperature piezoelectric ceramic materials. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a La / Nd / Ce / Ga / V / Sn / W doped Bi3TiNbO9 high-temperature piezoelectric ceramic material, targeting the Bi at the A-site of the Bi3TiNbO9 ceramic material. 3+ Ions, using La with 12 coordination3+ 、Nd 3+ Ce 4+ Composition of complex high-valence ions [La 0.2 Nd 0.4 Ce 0.4 ] 3.4+ Doping substitution is performed on Ti at the B site. 4+ 、Nb 5+ Ions, using Ga with 6 coordination groups 3+ V 5+ Sn 4+ W 6+ Composition of complex high-valence ions [Ga 0.3 V 0.7 ] 4.4+ 、[Sn 0.35 W 0.65 ] 5.3+ By doping and substituting the material, the piezoelectric properties and high-temperature resistivity can be improved while maintaining a high Curie temperature through the above-mentioned composite doping modification, thereby providing a novel, environmentally friendly piezoelectric ceramic material with excellent comprehensive electrical properties. Another object of the present invention is to provide a method for preparing the above-mentioned La / Nd / Ce / Ga / V / Sn / W doped Bi3TiNbO9 high-temperature piezoelectric ceramic material.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] This invention provides a La / Nd / Ce / Ga / V / Sn / W doped Bi3TiNbO9 high-temperature piezoelectric ceramic material, with La having 12 coordination sites. 3+ 、Nd 3+ Ce 4+ The complex high-valence ion [La] 0.2 Nd 0.4 Ce 0.4 ] 3.4+ Bi3TiNbO9 with A-site doping substitution 3+ Ions, with Ga having 6 coordination 3+ V 5+ Sn 4+ W 6+ Composition of complex high-valence ions [Ga 0.3 V 0.7 ] 4.4+ 、[Sn 0.35 W 0.65 ] 5.3+ Ti doping replaces the B site in Bi3TiNbO9 4+ 、Nb 5+ The ions form a general chemical formula of Bi. 3-x [La 0.2 Nd0.4 Ce 0.4 ] x Ti 1-y [Ga 0.3 V 0.7 ] y Nb 1-z [Sn 0.35 W 0.65 ] z O9, where 0.05≤x≤0.085, 0.015≤y≤0.03, and 0.03≤z≤0.07.

[0007] In the above scheme, the d of the piezoelectric ceramic material of the present invention 33 ≥21.3pC / N, T C ≥893℃; resistivity (ρ) at 500℃ ≥3.1×10 7 Ω·cm, dielectric loss (tanδ) ≤ 0.25%; d after annealing at 800℃ 33 ≥17.9pC / N.

[0008] Another objective of this invention is achieved through the following technical solution:

[0009] The method for preparing the La / Nd / Ce / Ga / V / Sn / W doped Bi3TiNbO9 high-temperature piezoelectric ceramic material provided by the present invention includes the following steps:

[0010] (1) Preparation of pre-synthesized precursor powder

[0011] Bi₂O₃, TiO₂, Nb₂O₅, La₂O₃, Nd₂O₃, CeO₂, Ga₂O₃, V₂O₅, SnO₂, and WO₃ are used as raw materials corresponding to Bi, Ti, Nb, La, Nd, Ce, Ga, V, Sn, and W in the general chemical formula. The amount of Bi₂O₃ used in the raw materials is 1.0–1.5 wt% more than the stoichiometric amount in the general chemical formula, while the amounts of the other raw materials are the stoichiometric amounts in the general chemical formula. After the raw materials are prepared in this manner, they are ball-milled once using anhydrous ethanol as the ball milling medium. The resulting material is dried, sieved, pressed into shape, and then placed in a sealed crucible for calcination. The calcined material is then ground, sieved, and ball-milled a second time. The resulting material is dried, ground, and sieved to obtain the pre-synthesized precursor powder.

[0012] (2) Preparation of high temperature piezoelectric ceramic materials

[0013] The pre-synthesized precursor powder is loaded into a graphite mold and sintered in a spark plasma sintering furnace using a two-step sintering method to obtain a carbon-containing sintered product. Then, the carbon-containing sintered product is placed in a conventional high-temperature furnace for decarburization calcination in an air atmosphere to obtain a decarburized sintered product. Finally, the decarburized sintered product is subjected to polarization treatment to obtain a high-temperature piezoelectric ceramic material.

[0014] Further, in step (1) of the preparation method of the present invention, the pressing pressure is 4-6 MPa; the calcination treatment is carried out by heating at 5℃ / min to 800-820℃ in an oxidizing atmosphere and holding for 3-5 hours. In step (2), the two-step sintering method is carried out by heating at 100℃ / min to the first platform temperature of 840-860℃ in a discharge plasma sintering furnace with a pressure of 55-60 MPa and a DC pulse current of 600-650A, holding for 1-2 minutes, then cooling for 2-3 minutes to the second platform temperature of 740-760℃, holding for 8-10 minutes, then cooling at 50℃ / min to 600℃, stopping the DC pulse current, releasing the pressure, and cooling to room temperature with the furnace; the decarburization calcination treatment is carried out by heating at 5℃ / min to 650-700℃ in an air atmosphere and holding for 2.5-3 hours, and then cooling to room temperature with the furnace.

[0015] Further, in step (2) of the preparation method of the present invention, the polarization treatment is as follows: first, the surface of the decarburized calcined product is polished; then, an electrode coating treatment is performed, that is, silver electrodes are applied to the upper and lower surfaces of the polished decarburized calcined product; then, the temperature is increased to 740-760℃ at 5℃ / min for calcination, and the temperature is held for 20-30min, and then cooled to room temperature in the furnace; finally, polarization is performed in high-temperature silicone oil at 160-180℃ with a DC voltage of 10-15kV / mm for a polarization time of 25-35min.

[0016] The product was prepared using the above-mentioned method for preparing La / Nd / Ce / Ga / V / Sn / W doped Bi3TiNbO9 high-temperature piezoelectric ceramic material.

[0017] The present invention has the following beneficial effects:

[0018] (1) During the preparation of Bi3TiNbO9 piezoelectric ceramic materials, bismuth volatilization at high temperatures inevitably leads to the formation of bismuth vacancies, resulting in oxygen vacancy defects. To address this phenomenon, this invention employs three measures: ① During batching, the amount of Bi raw material is increased by 1.0–1.5 wt% compared to the stoichiometric amount in the general chemical formula to compensate for bismuth volatilization; ② A-site Bi is used... 3+ High-valence complex ions [La] 0.2 Nd 0.4 Ce 0.4 ] 3.4+Doping and substitution to increase the mixing entropy of the material; ③ Using valence ratio B-site Ti 4+ 、Nb 5+ High-concentration complex ions [Ga 0.3 V 0.7 ] 4.4+ 、[Sn 0.35 W 0.65 ] 5.3+ Doping and substitution further increases the mixing entropy of the material. Measures ② and ③ above can also cause defects at sites A and B to result in a perovskite-like layer (A... m- 1B m O 3m+1 ) 2- Electrons are generated, thereby strengthening the bismuth-oxygen layer (Bi2O2). 2+ and perovskite-like layer (A m-1 B m O 3m+1 ) 2- The interaction between them. The above three measures can achieve the following objectives: ① reduce the oxygen vacancy concentration, thereby increasing the resistivity; ② reduce the carrier concentration inside the ceramic, further increasing the resistivity; ③ regulate the growth behavior of the grains, causing them to locally generate polarized nanodomains, thereby enhancing the piezoelectric activity. Thus, a high-performance Bi3TiNbO9 high-temperature piezoelectric ceramic material was ultimately obtained.

[0019] (2) The present invention adopts advanced spark plasma sintering technology. The sintering process adopts a two-step sintering method. The sintering technology requires low sintering temperature and short time, thus the energy consumption is low. After sintering, the grains are fine and uniform, the material density is high, and Bi3TiNbO9 high temperature piezoelectric ceramic material with excellent performance can be obtained.

[0020] (3) The La / Nd / Ce / Ga / V / Sn / W doped Bi3TiNbO9 piezoelectric ceramic material of the present invention has a Curie temperature above 893℃ and a piezoelectric constant d 33 ≥21.3pC / N, d after annealing at 800℃ 33 ≥17.9 pC / N; resistivity at 500℃ ≥3.1×10 7 The dielectric loss is ≤0.25% (Ω·cm). This material exhibits excellent high-temperature stability, fully meeting the application requirements of piezoelectric ceramic transducer elements in high-temperature environments, and has broad application prospects in high-temperature electronic equipment.

[0021] (4) The preparation method of the present invention adopts advanced ceramic preparation technology, with low firing temperature, low preparation cost, simple and easy operation, and easy control of influencing factors. It is suitable for large-scale industrial production and is conducive to promotion and application. Attached Figure Description

[0022] The present invention will now be described in further detail with reference to the embodiments and accompanying drawings:

[0023] Figure 1 These are the XRD phase diagrams of the piezoelectric ceramic materials in the embodiments and comparative examples of this invention;

[0024] Figure 2 The piezoelectric constant d of the piezoelectric ceramic materials in the embodiments and comparative examples of this invention is... 33 Curve showing temperature variation. Detailed Implementation

[0025] Example 1:

[0026] This embodiment describes a La / Nd / Ce / Ga / V / Sn / W doped Bi3TiNbO9 high-temperature piezoelectric ceramic material with the general chemical formula Bi. 2.94 [La 0.2 Nd 0.4 Ce 0.4 ] 0.06 Ti 0.975 [Ga 0.3 V 0.7 ] 0.025 Nb 0.96 [Sn 0.35 W 0.65 ] 0.04 The preparation method of this piezoelectric ceramic material, O9, includes the following steps:

[0027] (1) Preparation of pre-synthesized precursor powder

[0028] Bi₂O₃, TiO₂, Nb₂O₅, La₂O₃, Nd₂O₃, CeO₂, Ga₂O₃, V₂O₅, SnO₂, and WO₃ with a purity of 99.9% were used as raw materials corresponding to Bi, Ti, Nb, La, Nd, Ce, Ga, V, Sn, and W in the above general chemical formulas. The amount of Bi₂O₃ used was 1.2 wt% more than the stoichiometry in the general chemical formulas, while the amounts of the other raw materials were the stoichiometry in the general chemical formulas. After mixing the raw materials according to this ratio, anhydrous ethanol was used as the ball milling medium, with a ball:material:anhydrous ethanol ratio. The ratio of the materials was 4:1:3. The materials were ball-milled once at 400 r / min in a planetary ball mill for 24 h. The resulting material was dried, passed through an 80-mesh sieve, and pressed into shape under a pressure of 4 MPa. It was then placed in a sealed crucible and calcined at 820 °C at a rate of 5 °C / min in an oxidizing atmosphere for 4.5 h. The calcined material was then ground, passed through an 80-mesh sieve, and then ball-milled a second time using the same process as the first ball milling. The resulting material was dried, ground, and passed through an 80-mesh sieve to obtain the pre-synthesized precursor powder.

[0029] (2) Preparation of high temperature piezoelectric ceramic materials

[0030] (2-1) Take 0.8g of the above pre-synthesized precursor powder and put it into a cylindrical graphite mold with a diameter of 20mm. Place it in a spark plasma sintering furnace. Under the conditions of a pressure of 60MPa and a DC pulse current of 620A, first heat up to the first platform temperature of 840℃ at 100℃ / min, hold for 2min, then rapidly cool down to the second platform temperature of 750℃ after 2min, hold for 8min, then cool down to 600℃ at 50℃ / min, stop the DC pulse current, then release the pressure and cool down to room temperature with the furnace to obtain carbon-containing calcined products.

[0031] (2-2) The above carbon-containing calcined products are placed in a common high-temperature furnace and heated to 700°C at 5°C / min for decarburization calcination in air atmosphere. The temperature is maintained for 2.5 hours and then cooled to room temperature with the furnace to obtain decarburized calcined products.

[0032] (2-3) The above-mentioned decarburized calcined product is subjected to the following polarization treatment: First, the surface of the above-mentioned decarburized calcined product is polished; then, electrode coating treatment is performed, that is, silver electrodes are applied to the upper and lower surfaces of the polished decarburized calcined product; then, the temperature is raised to 740℃ at 5℃ / min and calcined, held for 25min, and cooled to room temperature in the furnace; finally, in high-temperature silicone oil at 180℃, a DC voltage of 10~15kV / mm is applied for polarization, and the polarization time is 25min, thus obtaining the high-temperature piezoelectric ceramic material.

[0033] Example 2:

[0034] This embodiment presents a La / Nd / Ce / Ga / V / Sn / W doped Bi3TiNbO9 high-temperature piezoelectric ceramic material and its preparation method, which differs from Embodiment 1 in that:

[0035] (1) The chemical formula of the piezoelectric ceramic material in this embodiment is Bi. 2.93 [La 0.2 Nd 0.4 Ce 0.4 ] 0.07 Ti 0.98 [Ga 0.3 V 0.7 ] 0.02 Nb 0.94 [Sn 0.35 W 0.65 ] 0.06 O9.

[0036] (2) The calcination temperature in step (1) of the preparation method in this embodiment is 810℃.

[0037] (3) In step (2-1) of the preparation method in this embodiment, the calcination regime is as follows: under the conditions of pressure of 60MPa and DC pulse current of 620A, the temperature is first raised to the first platform temperature of 860℃ at 100℃ / min, held for 1min, then rapidly cooled to the second platform temperature of 760℃ after 2min, held for 8min, then cooled to 600℃ at 50℃ / min, the DC pulse current is stopped, the pressure is then released, and the furnace is cooled to room temperature to obtain carbon-containing calcined products.

[0038] Example 3:

[0039] This embodiment presents a La / Nd / Ce / Ga / V / Sn / W doped Bi3TiNbO9 high-temperature piezoelectric ceramic material and its preparation method, which differs from Embodiment 1 in that:

[0040] (1) The chemical formula of the piezoelectric ceramic material in this embodiment is Bi. 2.95 [La 0.2 Nd 0.4 Ce 0.4 ] 0.05 Ti 0.97 [Ga 0.3 V 0.7 ] 0.03 Nb 0.94 [Sn 0.35 W 0.65 ] 0.06 O9.

[0041] (2) The calcination temperature in step (1) of the preparation method in this embodiment is 800℃.

[0042] (3) In step (2-1) of the preparation method in this embodiment, the calcination regime is as follows: under the conditions of pressure of 60MPa and DC pulse current of 650A, the temperature is first raised to the first platform temperature of 860℃ at 100℃ / min, held for 1.5min, then rapidly cooled to the second platform temperature of 760℃ after 2min, held for 8min, then cooled to 600℃ at 50℃ / min, the DC pulse current is stopped, the pressure is then released, and the furnace is cooled to room temperature to obtain carbon-containing calcined products.

[0043] Comparative example:

[0044] An undoped high-temperature piezoelectric ceramic material with the general chemical formula Bi3TiNbO9 was used as a comparative example, and its preparation method was the same as in Example 1.

[0045] The XRD phase diagrams of the piezoelectric ceramic materials in the embodiments and comparative examples of this invention are as follows: Figure 1 As shown, from Figure 1As can be seen from the data, the diffraction peaks of the piezoelectric ceramic materials prepared in each embodiment and comparative example are in complete agreement with the standard spectrum PDF 00-039-0233, indicating that the obtained materials are single-phase Bi3TiNbO9 materials.

[0046] The piezoelectric constant d of the piezoelectric ceramic materials in the embodiments and comparative examples of the present invention 33 The curve of temperature change is as follows Figure 2 As shown. From Figure 2 It can be seen that, from room temperature to 600℃, the d of the piezoelectric ceramic material in the embodiments of the present invention... 33 The value decreases slightly with increasing temperature; at 800℃, d 33 The value remains above 84.0% of that at room temperature, indicating that the material has good temperature stability, which is beneficial for its application in high-temperature fields.

[0047] The performance test results of the piezoelectric ceramic materials in the embodiments and comparative examples of the present invention are shown in Table 1.

[0048] Table 1 Performance indicators of ceramic materials in the embodiments and comparative examples of the present invention

[0049]

Claims

1. A method for preparing a La / Nd / Ce / Ga / V / Sn / W doped Bi3TiNbO9 high-temperature piezoelectric ceramic material, characterized in that: The high-temperature piezoelectric ceramic material is composed of La with 12 coordination groups. 3+ 、Nd 3+ Ce 4+ The complex high-valence ion [La] 0.2 Nd 0.4 Ce 0.4 ] 3.4+ Bi3TiNbO9 with A-site doping substitution 3+ Ions, with Ga having 6 coordination 3+ V 5+ Sn 4+ W 6+ Composition of complex high-valence ions [Ga 0.3 V 0.7 ] 4.4+ 、[Sn 0.35 W 0.65 ] 5.3+ Ti doping replaces the B site in Bi3TiNbO9 4+ 、Nb 5+ The ions form a general chemical formula of Bi. 3-x [La 0.2 Nd 0.4 Ce 0.4 ] x Ti 1-y [Ga 0.3 V 0.7 ] y Nb 1-z [Sn 0.35 W 0.65 ] z O9, where 0.05≤x≤0.085, 0.015≤y≤0.03, 0.03≤z≤0.07; the preparation method includes the following steps: (1) Preparation of pre-synthesized precursor powder Bi₂O₃, TiO₂, Nb₂O₅, La₂O₃, Nd₂O₃, CeO₂, Ga₂O₃, V₂O₅, SnO₂, and WO₃ are used as raw materials corresponding to Bi, Ti, Nb, La, Nd, Ce, Ga, V, Sn, and W in the general chemical formula. The amount of Bi₂O₃ used in the raw materials is 1.0–1.5 wt% more than the stoichiometric amount in the general chemical formula, while the amounts of the other raw materials are the stoichiometric amounts in the general chemical formula. After the raw materials are prepared in this manner, they are ball-milled once using anhydrous ethanol as the ball milling medium. The resulting material is dried, sieved, pressed into shape, and then placed in a sealed crucible for calcination. The calcined material is then ground, sieved, and ball-milled a second time. The resulting material is dried, ground, and sieved to obtain the pre-synthesized precursor powder. (2) Preparation of high-temperature piezoelectric ceramic materials The pre-synthesized precursor powder is loaded into a graphite mold and sintered in a spark plasma sintering furnace using a two-step sintering method to obtain a carbon-containing sintered product. Then, the carbon-containing sintered product is placed in a conventional high-temperature furnace for decarburization calcination in an air atmosphere to obtain a decarburized sintered product. Finally, the decarburized sintered product is subjected to polarization treatment to obtain a high-temperature piezoelectric ceramic material.

2. The method for preparing La / Nd / Ce / Ga / V / Sn / W doped Bi3TiNbO9 high-temperature piezoelectric ceramic material according to claim 1, characterized in that: The pressing pressure in step (1) is 4-6 MPa; the calcination treatment is carried out by heating to 800-820℃ at 5℃ / min in an oxidizing atmosphere and holding for 3-5 hours.

3. The method for preparing La / Nd / Ce / Ga / V / Sn / W doped Bi3TiNbO9 high-temperature piezoelectric ceramic material according to claim 1, characterized in that: The two-step sintering method in step (2) is as follows: under the conditions of a discharge plasma sintering furnace pressure of 55-60 MPa and a DC pulse current of 600-650 A, the temperature is first raised to the first platform temperature of 840-860°C at 100°C / min and held for 1-2 min. Then, after 2-3 min, the temperature is cooled to the second platform temperature of 740-760°C and held for 8-10 min. Then, the temperature is lowered to 600°C at 50°C / min, the DC pulse current is stopped, the pressure is released, and the furnace is cooled to room temperature. The decarburization calcination treatment is carried out by raising the temperature to 650-700°C at 5°C / min in an air atmosphere and holding for 2.5-3 h. The furnace is then cooled to room temperature.

4. The method for preparing the La / Nd / Ce / Ga / V / Sn / W doped Bi3TiNbO9 high-temperature piezoelectric ceramic material according to claim 1, characterized in that: The polarization process in step (2) involves first polishing the surface of the decarburized product; then applying an electrode coating, i.e., applying silver electrodes to the upper and lower surfaces of the polished decarburized product; then calcining at 5°C / min to 740-760°C, holding for 20-30 min, and cooling to room temperature in the furnace; finally, polarizing in high-temperature silicone oil at 160-180°C with a DC voltage of 10-15 kV / mm for 25-35 min.

5. The product prepared using the method for preparing La / Nd / Ce / Ga / V / Sn / W doped Bi3TiNbO9 high-temperature piezoelectric ceramic material according to any one of claims 1-4, characterized in that: The piezoelectric ceramic material d 33 ≥21.3 pC / N T C ≥893℃; resistivity at 500℃ ( ρ ≥3.1×10 7 Ω·cm, dielectric loss (tan δ ≤0.25%; after annealing at 800℃ d 33 ≥17.9pC / N.

Images